---------- Forwarded message ---------- From: Amit Langote <amitlangot...@gmail.com> Date: Thu, Apr 3, 2014 at 1:53 PM Subject: Re: [GENERAL] Table Rewrite During ALTER TABLE ... ADD COLUMN ... DEFAULT NULL To: Tom Lane <t...@sss.pgh.pa.us> Cc: Postgres General <pgsql-gene...@postgresql.org>
On Thu, Apr 3, 2014 at 1:19 PM, Tom Lane <t...@sss.pgh.pa.us> wrote: > Amit Langote <amitlangot...@gmail.com> writes: >> On Thu, Apr 3, 2014 at 12:54 PM, Tom Lane <t...@sss.pgh.pa.us> wrote: >>> Some experimentation suggests that we are smart about "DEFAULT NULL" >>> unless the column type requires a length-coercion cast, in which >>> case the default expression involves a function call, and that doesn't >>> get elided. > >> Is there a warning about such behavior in the manual? >> Is it useful to include it somewhere (not sure where though)? > > We could just rephrase the ALTER TABLE docs to say that the table > rewrite is avoided if you omit the DEFAULT clause, rather than > saying that a null default works. > How does the attached sound? Wonder if a rewrite-warning is necessary? -- Amit
alter-table-doc-fix.patch
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